Abstract: A novel algorithm based on twist is presented for real-time task-space trajectory planning.Inheriting the notion of robot guidance,based on the background of object capture for space robot,the trajectory planning under multiple constraints can be accomplished relying only on the observation information of the line-of-sight.Firstly,a twist-based representation is established for a vector,based on which a novel 3D guidance law similar to proportional navigation is developed.The longitudinal acceleration is computed according to the guidance law,the lateral acceleration is computed based on safety considerations,and the real-time algorithm for trajectory generation is established by combining the two processes together.The generated trajectory is feasible and safe,and has certain optimizing properties.Simulation results demonstrate the effectiveness of the proposed algorithm.